1. Field of the Invention
The present invention, in general, relates to valve assemblies for the opening and closing of outlets and relates more particularly to a dump valve assembly adapted especially for use in combination with the drain outlet of a vehicle waste tank such as, for example, a lavatory holding tank.
2. Prior Art
Already known in the art are holding tank drainage systems for the removal of waste or sewage from, for instance, a lavatory holding tank used on a variety of vehicles such as aircraft, locomotives, lavatory service trucks, and the like. Typically, these systems invariably utilize stoppers or plugs to hermetically seal the drain or waste outlet prior to or following waste removal and flushing of the holding tank. It will be appreciated that in order to allow the waste tank to be serviced the stopper or plug will first have to be removed from the outlet, the latter usually including an integral nipple assembly which is coupled to a drain hose, or the like, during the emptying process of the tank. Removal of the stoppers or plugs, typically, is accomplished by means of mechanical equipment which engages the stopper or plug, preferably without the spilling of waste, and without any possible personal contact therewith.
The holding tank drain systems which are currently widely in use utilizes a nipple assembly formed integrally with the bottom of the waste or sewage holding tank and, depending upon the given construction of the nipple, i.e., a flanged or flangeless nipple, a cap or drain plug is employed to prevent waste or sewage leakage from the holding tank. To remove the cap or drain plug, a drain coupling is used. The drain coupling incorporates a nipple contacting portion and a handle which is keyed for engagement with the cap or plug to dislodge these sealing members from the nipple assembly. A special by-pass channel is provided in the coupling which enables the waste or sewage to be discharged from the tank via, for an example, by a hose coupled to the by-pass channel. A conventional drain coupling is, for instance, a Y-drain coupling which comprises a handle secured to an elongated shaft which is keyed to mate with a slot provided in the cap or plug. Upon engagement with the keyed shaft end and the slotted cap or plug, the handle is withdrawn which removes the cap or plug from the nipple, the latter remaining on the keyed shaft end for subsequent repositioning of the cap or plug following waste removal and cleaning of the tank. Upon dislodgement of the cap or plug from the nipple, the waste or sewage is drained from the tank via the drain "Y" fitting, the latter being coupled to a hose, pipe, or the like, by means of a special coupling assembly detachably mounted on the drain. Following waste removal and flushing of the tank, the shaft is raised and the cap or plug is repositioned on or in the nipple opening. Subsequently, the drain coupling is removed from the nipple assembly.
Although the above-discussed system provides a no-contact and no-spill waste removal arrangement tank, it will be appreciated that this system is complicated as regards the required manual operations to connect the drain coupling, to remove the cap or plug, to reposition the latter sealing members, and to again remove the drain coupling. Moreover, this type of coupling is uneconomical with regard to its construction, maintenance, parts, and manufacture.